Patterns of behavior in the Texas tortoise, Gopherus berlandieri: a multivariate ordination approach

2001 ◽  
Vol 79 (8) ◽  
pp. 1363-1371 ◽  
Author(s):  
Richard T Kazmaier ◽  
Eric C Hellgren ◽  
David R Synatzske
Keyword(s):  
Correspondence Analysis ◽  
Wildlife Management ◽  
Environmental Variables ◽  
Detrended Correspondence Analysis ◽  
Behavioral Variability ◽  
Significant Variable ◽  
Active Behavior ◽  
Management Area ◽  
Dry Conditions ◽  
Patterns Of Behavior

We compared the distribution of 19 categories of behavior exhibited by 47 adult Texas tortoises (Gopherus berlandieri) over 3 years with the use of detrended correspondence analysis (DCA) and canonical correspondence analysis (CCA). DCA revealed a gradient from passive to active behavior along axis 1. Tortoises were more active in 1994 and less active in 1996. This pattern was likely due to the extremely hot and dry conditions in 1996. Year was the most significant variable explaining variability in behavior when sex, age, size, year, and grazing treatment (pastures grazed versus ungrazed by cattle) were used as environmental variables in CCA. Age, size, and grazing treatment were not significant variables in CCA. Tortoises used proportionally more burrows, shallow surface depressions termed pallets, and cavity pallets, and ate more cactus in 1996. More foraging and active behaviors, like courtship, were observed in 1994. Sex was a significant variable in explaining behavioral variability after the effects of year were controlled for. Males tended to exhibit more active behaviors than females. Our analyses suggested that the grazing regime used in Chaparral Wildlife Management Area did not affect the patterns of behavior exhibited by this protected tortoise.

Ordination as a tool for substantiating and interpreting floristic classifications: a case study

Bothalia ◽  
1990 ◽  
Vol 20 (2) ◽  
pp. 223-227 ◽  
Author(s):  
G. B. Deall ◽  
G. K. Theron
Keyword(s):  
Correspondence Analysis ◽  
Environmental Variables ◽  
Detrended Correspondence Analysis

Detrended Correspondence Analysis ordination is used as a tool for substantiating the authenticity of hierarchical syntaxa derived from a phytosociological classification of the vegetation of the Eastern Transvaal Escarpment in the Sabie area. Ecological interpretation of syntaxa is facilitated by superimposing environmental variables on axes of ordination.

scholarly journals Environmental Determinates of Distribution for Dragonfly Nymphs (Odonata: Anisoptera) in Urban and Non-Urban East Texas Streams, USA

Hydrobiology ◽  
2022 ◽  
Vol 1 (1) ◽  
pp. 76-88
Author(s):  
David E. Bowles ◽  
Leroy J. Kleinsasser
Keyword(s):  
Water Quality ◽  
Correspondence Analysis ◽  
Environmental Variables ◽  
Detrended Correspondence Analysis ◽  
Urban Streams ◽  
T Test ◽  
Benthic Habitats ◽  
Relationship Of ◽  
Quality Assessments ◽  
Dragonfly Species

We collected environmental and habitat data for nymphs of 12 dragonfly species (Odonata: Anisoptera) from 91 stream sites throughout eastern Texas, including urban and non-urban locations. Understanding the relationship of dragonflies to habitat structure and other environmental variables is crucial for the purpose of conserving these insects and better using them as predictive tools for water quality assessments, and refining tolerance values. The objectives of this study were to determine the key environmental variables influencing the diversity and distribution of dragonflies in eastern Texas streams, and further determine if differences in those factors could be observed between urban and nonurban sites. We collected samples separately from benthic habitats and woody snag habitats. Significantly fewer sites were observed to have dragonfly species on snag habitat (mean = 1.25) compared to benthic samples (mean = 14.67) (t-test, p = 0.001). The number of dragonfly species collected among non-urban streams (mean = 9.83) was not significantly different than urban streams (mean = 6.08; t-test, p = 0.07). Detrended correspondence analysis of benthic and snag habitat data collected from non-urban and urban locations showed that most of the species are oriented most closely to benthic habitats in non-urban streams. Snag habitat was shown to be poorly ordinated for all of the species. A canonical correspondence analysis of 29 water quality and habitat variables as environmental determinants of dragonfly diversity and distribution showed that distributional relationships among species are complex and often described by multiple environmental factors.

Environmental factors including management practices as correlates of weed community composition in spring seeded crops

1992 ◽  
Vol 70 (10) ◽  
pp. 1931-1939 ◽  
Author(s):  
M. R. T. Dale ◽  
A. G. Thomas ◽  
E. A. John
Keyword(s):  
Community Composition ◽  
Correspondence Analysis ◽  
Canonical Correspondence Analysis ◽  
Environmental Variables ◽  
Management Practices ◽  
Geographic Region ◽  
Climatic Conditions ◽  
Weed Species ◽  
Weed Communities ◽  
Seed Crops

The relationship between the weed communities and environmental variables such as soil, crop, and management was investigated in two provinces of Canada. The frequencies of weed species were recorded in cereal and oilseed fields in Saskatchewan (2244 fields over 4 years) and Manitoba (864 fields over 3 years), Canada. Information on some of the physical characteristics of the fields and on the management practices imposed on them was also collected, in part by questionnaire. The two kinds of data were ordinated together using canonical correspondence analysis to assess the relationships between the species and the environmental variables. In the Saskatchewan data, there was a clear and consistent separation of the species into groups along an axis correlated with soil zone and the associated climatic gradient. In the Manitoba data, the same groups of species did not separate as clearly or as consistently, although geographic region was a major determinant of the weed communities. The greater variability may be due to the fact that the gradient of soil types is much more restricted in Manitoba and not as closely correlated with climatic conditions. In both provinces, culture practices were less important as correlates of the weed community composition than soil type or, to a certain extent, the previous crop. Key words: canonical correspondence analysis, cereal crops, oil seed crops.

Models of the distribution and abundance of ground-dwelling mammals in the eucalypt forests of north-eastern New South Wales in relation to environmental variables

2002 ◽  
Vol 29 (3) ◽  
pp. 313 ◽  
Author(s):  
P. C. Catling ◽  
R. J. Burt ◽  
R. I. Forrester
Keyword(s):  
Environmental Variables ◽  
New South ◽  
New South Wales ◽  
Slope Position ◽  
Slope Aspect ◽  
Significant Variable ◽  
South Wales ◽  
North Eastern ◽  
Eucalypt Forests ◽  
A Site

Statistical models are presented of the distribution and abundance of ground-dwelling mammals in eucalypt forests in relation to environmental variables within an area of approximately 24 000 km2 in north-eastern New South Wales. Environmental variables are defined as climatic or topographic variables that may be useful to map the distribution of fauna. The environmental variables examined were season, temperature, rainfall, elevation, lithology, steepness of slope, position on slope, aspect and landform profile. The probability of recording some species was higher in spring than autumn and many species were in highest abundance in areas of low temperature (high elevation). Although aspect was a significant variable in a number of models, no species was absent from any aspect category. Mid-slopes down to and including creeks and drainage lines were particularly important for many species, as were areas with flatter terrain. Although we have modelled environmental variables only there will no doubt be longer-term interactions between habitat and environmental variables. Fundamentally, environmental variables will determine the type of habitat present at a site, and the distribution of canopy communities, at least, can be predicted from environmental variables. However, other studies have shown for ground-dwelling mammals that environmental variables contribute little and it is the state of the habitat locally, and particularly the understorey, that determines their presence and abundance at a site. The results are discussed in relation to similar models using habitat variables and in relation to the use of such models in the management of ground-dwelling fauna in forests.

scholarly journals Identification of the important environmental factors influencing natural vegetation succession following cropland abandonment on the Loess Plateau, China

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e10349
Author(s):  
Zhenguo Zhang ◽  
Mingming Wang ◽  
Jikai Liu ◽  
Xinwei Li
Keyword(s):  
Loess Plateau ◽  
Correspondence Analysis ◽  
Classification Tree ◽  
Detrended Correspondence Analysis ◽  
Vegetation Succession ◽  
Natural Vegetation ◽  
Vegetation Types ◽  
The Loess Plateau ◽  
Cropland Abandonment

Identification of typical vegetation succession types and their important influencing factors is an important prerequisite to implement differential vegetation and soil management after land abandonment on the Loess Plateau, China. However, there is no reported study specifically on the identification of vegetation types and their important factors as well as the thresholds of the important factors for classification of the vegetation types, based on the medium- to long-term succession of natural vegetation after cropland abandonment. We collected vegetation and soil data on the natural vegetation with the longest 60-year-old forest communities that developed after cropland abandonment and analyzed the data using two-way indicator species analysis, detrended correspondence analysis, direct canonical correspondence analysis and classification tree model. The vegetation communities were classified into five distinct vegetation types, including Artemisia scoparia, Lespedeza davurica and Stipa bungeana, Artemisia giraldii pamp, Sophora viciifolia, Quercus liaotungensis and Biota orientalis. The years after cropland abandonment and soil C/N were further identified as important factors determining the types of vegetation. Likewise, it was observed that most of the investigated soil nutrient variables and soil texture-related variables improved with the vegetation succession while soil water in the surface layers showed a decreasing trend. These findings may provide an ecological basis for site-specific management of vegetation types after cropland abandonment in the medium-long term on the Loess Plateau. Our results encourage further exploration of vegetation succession and their important factors based on longer periods of vegetation succession after cropland abandonment under more soil and climatic conditions on the mountainous areas as the Loess Plateau.

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